Fuel-drawing device for a motor vehicle tank

ABSTRACT

The present invention provides a device for drawing-off fuel from a motor vehicle tank, the device comprising a drawing-off pump and a fine filter placed upstream from the pump, wherein the drawing-off pump is a brush-less pump.

[0001] The present invention relates to the field of systems for drawingfuel from a motor vehicle tank.

BACKGROUND OF THE INVENTION

[0002] Numerous systems have been proposed for this purpose.

[0003] In general, systems for drawing fuel from a motor vehicle tankcomprise an electric pump which sucks fuel in from the tank or from asupply situated within the tank.

[0004] The object of such a supply is to limit the amount of fuelmovement in the vicinity of the suction inlet of the pump, as can resultfrom acceleration, deceleration, or centrifugal force whenever thevehicle is not following a rectilinear path.

[0005] Furthermore, known fuel-drawing systems generally include acoarse filter or strainer placed at the inlet of the pump, and a finefilter for guaranteeing the quality of the fuel that is forwarded to theengine.

[0006] In particular, such fuel-drawing systems have been proposed inwhich the fine filter is situated downstream from the electric pump,e.g. as described in document WO A 99/01658.

[0007] Known fuel-drawing systems have already given good service.

[0008] Nevertheless they do not give total satisfaction.

[0009] In particular, and in spite of a great deal of research, nosatisfactory answer has yet been found to the various calls for progressto which the automobile industry is subject.

[0010] Firstly, it should be observed that when the fine filter issituated downstream from the pump, i.e. on the outlet duct therefrom,the fine filter is placed under pressure and its housing mustconsequently have mechanical strength that is suitable for withstandingthe stresses due to said pressure.

[0011] That has led to a preference for putting the fine filter notdownstream from the pump, but upstream therefrom, i.e. but at its inlet.That makes it possible to reduce certain stresses on the fine filterhousing, and, where appropriate, also to omit the inlet strainer.

[0012] However, placing the fine filter upstream from the pump givesrise to other problems that have not yet been solved in satisfactorymanner.

[0013] Firstly, when the fine filter is placed upstream from thedrawing-off pump, any polluting mechanical element escaping from thepump will reach the carburetor or the injectors and can disturboperation thereof.

[0014] Secondly, the fine filter is sometimes the subject of significantclogging if it is placed upstream from the pump, particularly when theelectric pump is associated with a supply which is itself fed by a jetpump, for example, receiving an inlet flow coming directly or indirectlyfrom the outlet of the electric pump.

[0015] Thirdly, on first starting of the system, or indeed after thesystem has become un-primed because of a low level of fuel, if the finefilter is situated upstream from the pump, then the electric pump mustsuck in a large volume of air which corresponds substantially to thevolume of the housing for the fine filter.

[0016] Fourthly, it should be observed that until now, most electricpumps used in fuel-drawing systems have been rotary gear pumps. Suchpumps operate on the principle of sucking liquid into the space lyingbetween two consecutive teeth and then in causing it to pass to adelivery section.

[0017] However, nowadays, there is a strong demand for rotary gear pumpsto be replaced by turbine or centrifugal pumps that can present genuineadvantages. Turbine or centrifugal pumps are machines in which therotation of a wheel or a rotor generates pressure and speed conditionsthat determine how a liquid flows in a circuit, with the magnitude ofthe flow being the result of equilibrium between the useful energydelivered by the pump per unit mass and the resistive energy per unitmass of the circuit.

[0018] Furthermore, nowadays, in numerous configurations, attempts atusing turbine or centrifugal pumps for drawing fuel do not givesatisfaction because of the problems of priming that are inherent tothis type of pump. This problem is particularly acute for systems inwhich the fine filter is situated upstream from the pump because of thehead loss generated by the filter.

[0019] Fithly, it should be emphasized that turbine or centrifugal pumpsgenerally possess a degassing orifice. When the pump is stopped, thepresence of such a degassing orifice on the pump housing leads tocontamination not only of the inside volume of the pump, but also of atleast a portion of the volume of the fine filter housing connectedthereto.

[0020] Sixthly, it should be emphasized that the presence of thedegassing orifice in the pump housing can lead to a risk of the positivereserve associated with the pump emptying out via said degassingorifice, unless special precautions are taken.

OBJECTS AND SUMMARY OF THE INVENTION

[0021] An object of the present invention is to improve knownfuel-drawing systems in order to eliminate the above-specified drawbacksthat are inherent to the prior art.

[0022] In the context of the present invention, this object is achievedby a device for drawing-off fuel from a motor vehicle tank, the devicecomprising a drawing-off pump and a fine filter placed upstream from thepump, wherein the drawing-off pump is a brush-less pump.

[0023] According to an advantageous characteristic of the presentinvention, the drawing-off pump is a pilot operated pump.

[0024] According to an advantageous characteristic of the presentinvention, the drawing-off pump is pilot operated in such a manner thatthe flow of fuel passing through the pump is close to the minimum flowrequired for proper operation of the device.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Other characteristics, objects, and advantages of the presentinvention will appear on reading the following detailed description andon observing the accompanying drawings, which are given as non-limitingexamples, and in which:

[0026]FIG. 1 is a diagrammatic vertical section view through adrawing-off device constituting a first embodiment of the presentinvention;

[0027]FIG. 2 is a similar vertical section view of a device constitutinga second embodiment of the present invention;

[0028]FIG. 3 is a similar vertical section view of a third embodiment ofthe present invention, shown on non-coplanar planes referenced 3-3 inFIG. 4;

[0029]FIG. 4 is a horizontal cross-section view through the FIG. 3device;

[0030]FIG. 5 is a diagrammatic longitudinal axial section view through aconventional jet pump of the prior art;

[0031]FIG. 6 is a diagrammatic longitudinal axial section view of a jetpump in accordance with the present invention; and

[0032]FIG. 7 is a diagrammatic longitudinal axial section view of a jetpump constituting a preferred variant of the present invention.

MORE DETAILED DESCRIPTION

[0033] As mentioned above, the device of the present invention comprisesan electric drawing-off pump 100 and a fine filter 210 placed upstreamfrom the pump, i.e. at the inlet thereof.

[0034] Various configurations of the fine filter 210 are described ingreater detail below.

[0035] Furthermore, in the context of the present invention, thedrawing-off pump 100 is a brush-less electric pump. Such a pump is wellknown to the person skilled in the art. Essentially, it comprises astator with coils and a rotor with a magnet.

[0036] The use of a brush-less pump 100 makes it possible to limit therisk of allowing foreign bodies to enter into the fuel or the injectors,and in particular shavings of metal or of plastics material that mightbe torn off during displacement of the brushes on an associatedcollector, in a conventional pump with brushes.

[0037] Naturally, this advantage becomes of great importance when thefine filter 210 is placed upstream from the drawing-off pump 100 and notdownstream therefrom.

[0038] Furthermore, in the context of the present invention, thedrawing-off pump 100 is preferably a pilot operated pump.

[0039] Even more precisely, the drawing-off pump 100 is pilot operatedin such a manner that the flow of fuel passing through it, andconsequently also passing through the fine filter 210 placed upstreamtherefrom, is substantially equal to the flow required for properoperation as a function of the instantaneous consumption of the engine.

[0040] Thus, when the drawing-off pump 100 sucks from a supply fed by ajet pump that receives an inlet flow coming directly or indirectly fromthe outlet of the drawing-off pump, the drawing-off pump is pilotoperated so as to deliver a flow that varies in such a manner that theflow passing through it and through the fine filter is substantiallyequal to the sum of the instantaneous consumption of the engine plus theauxiliary flow required for enabling the jet pump to operate. (The term“instantaneous consumption” of the engine is used herein to mean theactual instantaneous consumption of the engine, plus, where appropriate,any additional flow Qr that needs to be sent towards the engine in orderto ensure that its injectors operate properly, but that is not actuallyconsumed in practice, being returned to the drawing-off point (see FIG.1)).

[0041] In contrast, when the drawing-off pump 100 takes fuel directlyfrom the tank, the drawing-off pump is pilot operated so as to deliver aflow that varies in such a manner that the flow which passes through thepump and through the fine filter is substantially equal to theinstantaneous consumption of the engine. (In this case also, the term“instantaneous consumption” of the engine is used to mean the effectiveinstantaneous consumption of the engine plus, where appropriate, anyadditional flow Qr that is sent to the engine in order to ensure thatits injectors operate properly, but that is not consumed in practice,being returned to the drawing-off point (see FIG. 1)).

[0042] Thus, the present invention serves to limit the flow rate throughthe fine filter 210, and therefore serves to limit the head lossesthrough the filter 210, the pressure at the inlet to the fine filter,the inlet pressure to the pump 100, and also clogging of the fine filter210.

[0043] The drawing-off pump 100 can be pilot operated in variousdifferent ways.

[0044] The drawing-off pump 100 can be pilot operated by a pressure orflow rate sensor placed at the outlet from the pump. In principle, sucha technique for regulating a pump is known to the person skilled in theart. It is therefore not described in detail below. It is merelyrecalled at this point that such regulation generally requires the pumpto deliver some minimum flow rate on a continuous basis in order toensure that it operates properly.

[0045] In another variant, the drawing-off pump 100 can be pilotoperated by a reference coming from an engine control module, whichreference is representative of the instantaneous consumption required bythe engine. Under such circumstances, the pump 100 can be pilot operatedfrom the control signal on the basis of curves of the pressure/flow rateor electrical current/speed kind.

[0046] Various embodiments of the drawing-off device of the presentinvention are described below and shown in the accompanying figures.

[0047] The description begins with the embodiment shown in accompanyingFIG. 1.

[0048] In FIG. 1, there can be seen a vertical axis pump 100. Mostpreferably it constitutes a pump turbine or centrifugal type of pump. Asmentioned above, such a turbine or centrifugal pump possesses a wheel orrotor suitable for producing pressure and speed conditions thatdetermine the flow of fuel in a circuit.

[0049] The inlet 110 of the pump 100 is placed at the bottom end of thepump. The outlet 120 is situated at the top end of the pump.

[0050] The pump 100 has a degassing orifice 130 which opens to theoutside of the pump housing and which is situated in the vicinity of thebottom portion of the pump 100, just above the inlet orifice 110.

[0051] Accompanying FIG. 1 also shows a generally ring-shaped filterhousing 200 centered on a vertical axis.

[0052] The housing 200 is defined essentially by a radially outercylindrical wall 202, a radial inner cylindrical wall 204 coaxial withthe above-specified wall 202, and two generally horizontal partitions206 and 208 that are ring-shaped, respectively defining bottom and topportions of the housing 200.

[0053] The ring 208 is connected in leaktight manner to the top edges ofthe two cylindrical partitions 202 and 204.

[0054] The ring 206 is likewise connected to the bottom edge of theouter cylindrical partition 202. However, as described in greater detailbelow, it is not connected to the bottom of the radially innercylindrical wall 204.

[0055] The housing 200 houses an annularly-shaped filter 210. However,as explained below in particular with reference to FIGS. 3 and 4, thehousing 200 and the filter 210 could be of some other shape.

[0056] In FIG. 1, the pump 100 is placed in the central cavity 220 ofthe filter housing 200, i.e. the cavity defined inside the radiallyinner wall 204.

[0057] Leakproof connections are provided between each of the tworing-shaped walls 206, 208 of the housing 200 and the bottom and topportions respectively of the filter 210.

[0058] Thus, the housing 200 defines two chambers 240, 250 comprisingrespectively a radially inner chamber and a radially outer chamberrelative to the filter 210.

[0059] The radially outer chamber 240 serves as an inlet chamber for thehousing 200.

[0060] The radially inner chamber 250 serves as an outlet chamber.

[0061] For this purpose, in the central portion of the housing 200 thebottom ring-shaped wall 206 is extended by a leakproof partition 207,while the radially inner cylindrical wall 204 which defines the outletchamber 250 and which is interrupted beyond the partition 207 isextended by a horizontal wall 209 parallel to the abovementionedpartition 207.

[0062] The two partitions 207, 209 thus define a cylindrical chamber 205which communicates with the outlet chamber 250 of the filter housing.The inlet 110 of the pump opens out into said chamber 205. Furthermore,the partition 209 surrounds the inlet 110 of the filter in leaktightmanner.

[0063] The inlet chamber 240 of the filter housing can be filled by anyappropriate means from the tank 300.

[0064] The inlet chamber 240 is preferably filled using a jet pump 260of general structure that is conventional.

[0065] The jet pump 260 possesses a converging nozzle 262 forming adriving Venturi which is fed with fuel, e.g. from a branch connection270 connected to the outlet of the pump 100. The jet pump 260 alsopossesses a suction flow inlet 264 at its bottom portion which isprotected by a check valve 280 such as an umbrella valve oriented toallow fuel to be transferred from the tank 300 towards the internalchamber of the jet pump 260 and then towards the inlet chamber 240,while preventing fuel from flowing in the opposite direction, i.e. fromthe inlet stage 240 and the inside volume of the jet pump 260 backtowards the tank 300.

[0066] Finally, the jet pump 260 possesses a delivery outlet 266 whichopens out into the inlet chamber 240 of the filter housing 200.

[0067] In a variant embodiment, the delivery outlet 266 of the jet pump260 can be extended by a vertical pipe whose top end is situated in thevicinity of the top of the housing 200. Under such circumstances, thereis no need to place a check valve 280 at the inlet for the sucked-inflow 264. Nevertheless, such a check valve can be provided at anarbitrary point on the inside wall of the housing 200 defining the inletchamber 240 so as to allow fuel to be transferred from the tank towardsthe inlet chamber 240 when the level in the tank 300 is greater than thelevel in the inlet chamber 240.

[0068] It should also be observed that in the embodiment shown in FIG.1, the flow Qr of fuel that is not consumed by the engine is returnedvia a duct 290 to the inlet chamber 240 of the filter.

[0069] Nevertheless, in a variant, this flow Qr from the duct 290 couldbe used for feeding the jet pump 260, and more specifically for feedingthe converging nozzle forming the driving Venturi 262.

[0070] In another variant embodiment, it is possible to envisage usingthe return flow Qr in common with the branch flow Qi taken from theoutlet of the pump 100 to feed the driving Venturi 262 of the jet pump260 for the purpose of filling the inlet chamber 240 of the filter.

[0071] The flow of fuel Qp as sucked in through the inlet 110 of thepump 100 is equal to the sum of the flows Qm+Qr+Qi delivered via theoutlet 220.

[0072] The flow Qt from the outlet 266 of the jet pump 260 is equal tothe sum of the flow Qi coming from the branch connection 270 plus theflow Qa coming from the inlet 264.

[0073] To enable the filter housing 200 to be filled, the sum of thedelivery flow rate Qr plus the flow rate Qt from the jet pump 260 mustbe greater than the sum of the flow rate Qp sucked in through the inlet110 of the pump plus the flow Qf coming from the housing 200 via adegassing orifice 222 situated in the top portion of the housing 200,typically in the partition 208.

[0074] As can be seen on examining FIG. 1, the degassing orifice 130 ofthe pump 100 opens out into the central cavity 220 defined by theradially inner surface 204 of the filter housing 200.

[0075] It will also be observed on examining FIG. 1 that the structureof the present invention provides a large positive reserve volume forthe pump 100, equal to the volume of the housing 200.

[0076] As mentioned above, the degassing orifice 222 of the filterhousing 200 is placed in the top partition 208 and looks into the inletchamber 240.

[0077] This orifice 222 opens out into a duct 224 having a segment 225which is generally horizontal running over the top partition 208 andextended by a generally vertical segment 226 which runs over theradially inner wall 204 down to the base of the cavity 220. The endsegment 226 of the duct 224 thus possesses an opening 227 situated closeto the partition 208 in the vicinity of the degassing orifice 130 of thepump 100.

[0078] The opening 227 of the duct 224 is situated at a height that isequal to or lower than the height of the degassing orifice 130 of thepump 100.

[0079] The opening 227 of the duct 224 is preferably situated beneaththe level of the degassing orifice 130 of the pump 100. Also preferably,the diameter of the duct 124 is at least slightly greater than thediameter of the degassing orifice 130 of the pump 100.

[0080] By means of these characteristics, the duct 224 constitutes asiphon suitable for delivering the fuel present in the central cavity220 as defined by the pump housing 200 towards the inlet chamber 240 ofthe filter in the event of the pump 100 stopping, thereby preventingfuel entering the pump via the degassing orifice 130, which fuel mightcontaminate the pump 100.

[0081] When the system is filled for the first time, the filter housing200 is degassed via the orifice 222 and the duct 224 with the twosegments 225 and 226. Similarly, the pump 100 is degassed via theorifice 130.

[0082] When the pump 100 is stopped, the housing 200 defines a staticfuel reserve.

[0083] Furthermore, as mentioned above, the duct 224 forms a siphonsuitable for sucking away the fuel present in the central cavity 220towards the inlet chamber 240, thereby preventing said fuel being suckedinto the inside of the pump 100 via the degassing orifice 130.

[0084] It should also be observed that the siphon formed by the duct 224is assisted in this function by the internal pressure which existsinside the pump 100 when it is stopped.

[0085]FIG. 2 shows a variant embodiment of the present invention whichdiffers from the above-described embodiment shown in FIG. 1 essentiallyin that the return duct 290 is omitted and a pressure regulator 400 isprovided on the outlet of the pump, and more precisely on the branchconnection duct 270 used for feeding the driving Venturi 262 of the jetpump 260.

[0086] The pressure regulator 400 is designed to open and allow flowfrom the outlet of the pump 100 towards the driving Venturi 262 wheneverthe pressure at the outlet from the pump 100 is greater than athreshold, and on the contrary it closes so as to prevent this flowwhenever the outlet pressure from the pump 100 is below theabovementioned threshold.

[0087] The regulator 400 can be implemented in various conventionalways. It is therefore not described in detail below.

[0088] Nevertheless, it should be observed that the regulator 400preferably comprises a housing which houses a flexible diaphragm urgedboth by a rated resilient member so as to bear against an outlet nozzle,and also by the fuel pressure that exists in the branch connection duct270 so as to move away from said outlet nozzle.

[0089] Thus, when the force generated on the diaphragm by the pressurethat exists in the branch connection duct 270 is greater than the forcegenerated by the rated resilient member, then the flexible diaphragm islifted off the outlet nozzle so as to allow flow towards the drivingVenturi 262, thereby feeding the pump 260.

[0090] In contrast, when the force generated by the flexible diaphragmof the pressure regulator 400 by the pressure that exists in the duct270 is less than the force applied by the rated resilient member, thenthe diaphragm is pressed against the outlet nozzle so as to prevent thejet pump 260 being fed.

[0091] The embodiment shown in FIGS. 3 and 4 is described below.

[0092] Firstly, this embodiment differs from those described above withreference to FIGS. 1 and 2 by the fact that it comprises a pump 100 witha jet pump 260 integrated therein and having its driving Venturi fed viaa pressure stage of the pump 100 and located so as to feed the inletchamber 240 of the filter as described above with reference to FIGS. 1and 2.

[0093] Secondly, the embodiment shown in FIGS. 3 and 4 differs from theembodiments described above with reference to FIGS. 1 and 2 by the factthat it has a filter 210 which instead of being in the form of anannulus surrounding the pump 100 is in the form of a crescent located onone side of the pump 100.

[0094] The embodiment shown in FIGS. 3 to 4 makes use of essentially thesame characteristics as those described above with reference to FIGS. 1and 2, and in particular it has a filter inlet chamber 240 fed by thejet pump 260 and provided with a degassing orifice 222 which opens outinto a siphon-forming duct 224, and the degassing orifice 130 of thepump 100 is placed in the environment of the opening 227 of the siphon224.

[0095] The description below relates to improvements in accordance withthe present invention that are specific to the jet pumps 260.

[0096] These improvements apply in particular to the embodiment shown inFIGS. 3 and 4.

[0097] Accompanying FIG. 5 shows the conventional structure for a jetpump.

[0098] Such a conventional jet pump, sometimes also referred to as aliquid ejector, is constituted in outline by the following coaxialelements:

[0099] a first converging Venturi 262 referred to as the driving Venturiand fed with fluid under pressure;

[0100] a second converging Venturi 267 referred to as the take-upVenturi surrounding the first and connected to a suction inlet 264 ofthe device;

[0101] a cylindrical section 268 referred to as the mixer; and

[0102] a diverging end portion 269 acting as a diffuser.

[0103] The throat of the driving Venturi 262 is generally locatedslightly upstream from the throat of the take-up Venturi 267, or elselevel with the throat of the take-up Venturi 267, or indeed where thethroat of the take-up Venturi 267 joins the mixer 268.

[0104] The flow feeding the driving Venturi 262 constitutes the drivingflow of the ejector. In this Venturi, pressure energy is transferredinto kinetic energy. The driving fluid at the outlet is thus in the formof a jet at high speed. By turbulent exchange of momentum, this jetentrains a quantity of liquid through the take-up Venturi 267, with thisquantity constituting the flow rate sucked in by the ejector. Within themixer 268, the exchange of momentum between the driving fluid and thesucked-in fluid continues and comes to an end, with the speeds of thesetwo jets progressively becoming equal. Ignoring losses, this mixingoperation takes place at constant pressure. In the end diverging portion269, a fraction of the kinetic energy of the mixture is converted intopressure energy by diffusion.

[0105] Known jet pump devices have already given good service.Nevertheless, they do not always give full satisfaction.

[0106] In particular, the Applicant has found that known jet pumps donot operate under satisfactory conditions when there is a high level ofback pressure on the outlet from the diffuser 269.

[0107] The present invention now has an additional object of proposing anovel jet pump that makes it possible to eliminate the drawbacks of theprior art.

[0108] This object is achieved in the context of the present inventionby a jet pump in which the take-up nozzle 267 is connected directly tothe diffuser, without any intermediate mixer.

[0109] According to another advantageous characteristic of the presentinvention, the jet pump has a large diffuser.

[0110] Accompanying FIG. 6 shows a body defining a channel centered onan axis O-O and comprising a first converging Venturi 262 forming adriving Venturi fed with fluid under pressure, a second convergingVenturi 267 forming a take-up Venturi surrounding the first andconnected to a suction inlet 264 of the device, and an end divergingportion 269 constituting a diffuser.

[0111] As mentioned above, the jet pump of the present invention is thuscharacterized by the absence of any mixer between the second convergingVenturi forming a take-up Venturi 267 and the end diverging portion 268forming a diffuser.

[0112] In the context of the present invention, the driving Venturi 262is preferably conical in shape, presenting a length lying in the range 4millimeters (mm) to 8 mm, and very advantageously a length that is aboutthe same as the diameter of the suction inlet 264.

[0113] The end of the driving Venturi 262 forming the outlet nozzle ofthe throat is preferably situated at a distance lying in the range 1 mmto 3 mm form the take-up Venturi.

[0114] The convergence angle B of the driving Venturi 262 preferablylies in the range 0° to 30°, and very advantageously is about 5°.

[0115] The take-up Venturi 267 is preferably defined by a toroidal cap.The radius of curvature R1 of this toroidal cap 267 preferably lies inthe range 1 mm to 2 mm, and very advantageously is about 1.6 mm. Thecurvature R1 of said toroidal cap is preferably tangential to thediffuser 269.

[0116] Furthermore, the inside radius R2 of the take-up Venturi 267, atits smallest section, preferably lies in the range 1.8 mm to 3.0 mm, andvery advantageously is about 2.0 mm to 2.6 mm.

[0117] Furthermore, the toroidal envelope of the take-up Venturi 267preferably occupies an angle A lying in the range 30° to 60° and veryadvantageously abut 45°.

[0118] The end diverging portion forming a diffuser 269 is preferablydefined by a conical envelope.

[0119] The length of the diffusing tube 269 preferably lies in the range10 mm to 40 mm, and is very advantageously about 18 mm.

[0120] Furthermore, the convergence angle C of the diffusing tube 269preferably lies in the range 2° to 10° and very advantageously it isabout 4°.

[0121]FIG. 7 shows a variant embodiment in which the jet pump body isfitted with a valve 50 designed to open in the event of the pressure inthe driving Venturi 262 being too high.

[0122] The valve 50 is formed in a length of tube 52 extending radiallyrelative to the axis O-O and connected to the body of the jet pumpupstream from the converging Venturi 262 forming the driving Venturi.

[0123] The tube 52 thus defines a chamber which opens out into thedriving Venturi 262. More precisely, the above-specified chamber definesa valve seat 54 facing radially outwards with a valve member 56 urgedthereagainst by a spring 58.

[0124] In the variant shown in FIG. 7, the valve member 56 is generallymushroom-shaped with a flared head resting against the valve seat 54 anda valve stem of smaller section serving to guide sliding of the valvemember 56 in a direction that is radial relative to the axis O-O andalso serving to support the spring 58.

[0125] Naturally, the valve 50 can be implemented in numerous differentways.

[0126] The valve is designed to open by the valve member 56 lifting offthe valve seat 54 in the event of the pressure inside the drivingVenturi 262 becoming excessive, and to close whenever the pressureinside the driving Venturi 262 drops below a determined threshold.

[0127] Naturally, the present invention is not limited to the particularembodiment described above, but extends to any variant in compliancewith the spirit of the invention.

1/ A device for drawing-off fuel from a motor vehicle tank, the devicecomprising a drawing-off pump and a fine filter placed upstream from thepump, wherein the drawing-off pump is a brush-less pump. 2/ A deviceaccording to claim 1, wherein the drawing-off pump comprises a statorwith windings and a rotor with a magnet. 3/ A device according to claim1, wherein the drawing-off pump is a pilot operated pump. 4/ A deviceaccording to claim 1, wherein the drawing-off pump is pilot operated todeliver a varying flow rate such that the flow of fuel passing throughthe drawing-off pump is close to the minimum flow required for properoperation of the device, as a function of the instantaneous consumptionof the engine. 5/ A device according to claim 1, wherein the drawing-offpump is pilot operated in such a manner that the flow passing through itand through the filter is substantially equal to the instantaneousconsumption of engine. 6/ A device according to claim 1, having areserve from which the drawing-off pump draws fuel, and a jet pumpdesigned to feed the reserve on receiving an inlet flow coming directlyor indirectly from the outlet of the drawing-off pump, said drawing-offpump being pilot operated in such a manner that the flow passing throughit is substantially equal to the sum of the instantaneous consumption ofthe engine thus the auxiliary flow required for operating the jet pump.7/ A device according to claim 1, wherein the drawing-off pump is pilotoperated by a pressure or flow rate sensor. 8/ A device according toclaim 1, wherein the drawing-off pump is pilot operated by a referencevalue coming from an engine control module. 9/ A device according toclaim 1, wherein: the housing of the filter possesses a degassingorifice in its top portion; the drawing-off pump also possesses adegassing orifice; and the filter housing is fitted with a duct whichextends the degassing orifice of the housing, opens out into a cavitycommon to the degassing orifice of the pump, and possesses an openingsituated at a height equal to or lower than the height of the degassingorifice of the pump, said duct being shaped to constitute a siphonsuitable for taking fuel in the vicinity of its opening towards theinside of the filter housing whenever the drawing-off pump is stopping.10/ A device according to claim 9, wherein the inlet chamber of thefilter housing is fed and pressurized by a jet pump. 11/ A deviceaccording to claim 9, wherein the drawing-off pump is a pump of theturbine or centrifugal type. 12/ A device according to claim 10, whereinthe jet pump is fed by a branch connection connected to the outlet ofthe drawing-off pump. 13/ A device according to claim 10, wherein thejet pump is fed by a return duct receiving the fuel that is not consumedby the engine. 14/ A device according to claim 10, wherein the jet pumpis fed both by a branch connection connected to the outlet of thedrawing-off pump and by a return duct which receives the fuel that isnot consumed by the engine. 15/ A device according to claim 10, whereinthe jet pump has its suction flow inlet fitted with a non-return valve.16/ A device according to claim 10, wherein the jet pump has its outletextended by a vertical tube whose end is situated close to the top ofthe filter housing. 17/ A device according to claim 9, wherein a returnduct receiving the fuel that is not consumed by the engine opens outinto the inlet chamber of the filter housing. 18/ A device according toclaim 9, wherein the siphon-forming duct has a horizontal segment whichcommunicates with the degassing orifice of the filter housing, and agenerally vertical segment whose bottom opening is situated in thevicinity of the bottom of a cavity defined by the fine filter housingand in which the drawing-off pump is situated. 19/ A device according toclaim 9, wherein the opening of the siphon-forming duct is situatedbelow the level of the degassing orifice of the drawing-off pump. 20/ Adevice according to claim 9, wherein the diameter of the siphon-formingduct is greater that the diameter of the degassing orifice of thedrawing-off pump. 21/ A device according to claim 9, wherein a pressureregulator is placed on a duct connected to the outlet of the drawing-offpump and connected to the driving Venturi of a jet pump serving to feedthe inlet chamber of the filter housing. 22/ A device according to claim9, wherein the degassing orifice of the filter housing opens out intothe inlet chamber thereof. 23/ A device according to claim 9, whereinthe degassing orifice of the drawing-off pump is situated at the bottomof the drawing-off pump housing in a cavity defined by the filterhousing. 24/ A device according to claim 1 of the type including a jetpump having a first converging Venturi forming a driving Venturi fedwith fluid under pressure, a second converging Venturi forming a take-upVenturi surrounding the first Venturi and connected to a suction inlet,and an end diverging portion acting as a diffuser, wherein the secondconverging Venturi forming a take-up Venturi is connected directly tothe end diverging portion acting as a diffuser, without any intermediatemixer.